<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>DOM对象转化成jQuery对象</title>
    <script src="../jquery-3.4.1.js"></script>
</head>
<body>
    <div>元素一</div>
    <div>元素二</div>
    <div>元素三</div>
</body>
<script>
    //通过$(dom)方法将普通的dom对象加工成jQuery对象之后，我们就可以调用jQuery的方法了
    var div = document.getElementsByTagName('div');//dom
    var $div = $(div);//jquery
    var $first = $div.first();
    $first.css('color','red');
</script>
</html>